'Sand Battery Could Solve Green Energy's Big Problem'

AmiMoJo writes: Finnish researchers have installed the world's first fully working 'sand battery' which can store green power for months at a time. The developers say this could solve the problem of year-round supply, a major issue for green energy. Using low-grade sand, the device is charged up with heat made from cheap electricity from solar or wind. The device has been installed in the Vatajankoski power plant which runs the district heating system for the area. Low-cost electricity warms the sand up to 500C by resistive heating (the same process that makes electric fires work). This generates hot air which is circulated in the sand by means of a heat exchanger. Sand is a very effective medium for storing heat and loses little over time. The developers say that their device could keep sand at 500C for several months. So when energy prices are higher, the battery discharges the hot air which warms water for the district heating system which is then pumped around homes, offices and even the local swimming pool.

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